Cumulative effects on sediment and associated chemical fluxes at the landscape scale: the role of geomorpological connectivity

环境科学当前的研究主题之一是自然和人为压力或压力源——如气候变化、森林和采矿等土地利用活动以及野火等自然事件——如何影响水资源和水生生态系统。这种兴趣是由于认识到大多数（如果不是全部）水体受到影响水量（如水流）和水质（如化学、沉积物浓度）的多重压力源（通常称为累积效应）的影响。本研究项目的目的是确定多种压力源对环境的累积影响，重点关注不列颠哥伦比亚省中部的奎斯奈尔河流域（QRB，约12,000平方公里）。整个研究项目将特别侧重于地貌连通性（如陆地与河流之间的联系，以及渠道内的联系）如何影响沉积物和相关化学物质的转移，如微量金属（如砷、铜、锌）、营养物质（如磷）和颗粒碳，这是由于QRB中的应激源作用造成的。一个项目将评估储存要素（特别是冰川前田、河岸缓冲带、洪泛平原和河床）在控制沉积物和相关化学物质如何在受气候变化和土地利用活动影响的景观中移动方面的作用。特别是，该项目将确定这些存储元素是否会减弱和/或改变物料流和命运。第二个项目将采用与沉积物示踪剂结合的嵌套监测方案，跟踪沉积物和化学品在农业、林业和采矿等特定土地利用活动下游的移动情况。第三个项目将利用前两个项目获得的经验信息和QRB现有的GIS平台，利用现有的空间分布式模型，在流域尺度上研究地貌连通性对沉积物和相关化学反应的作用。这项工作将使人们更好地了解在快速变化的世界中，流域是如何对累积效应作出反应的，这将有助于保护加拿大的水资源和水生栖息地。

One of the current research themes in environmental science is how natural and anthropogenic pressures or stressors - such as climate change, land-use activities like forestry and mining, and natural events like wildfires - affect water resources and aquatic ecosystems. This interest is driven by the recognition that most, if not all, water bodies are affected by multiple stressors (often termed cumulative effects) that impact water quantity (e.g. water flows) and water quality (e.g. chemistry, sediment concentrations). The objective of this research project is to determine the cumulative effects of multiple stressors on the environment by focusing on the Quesnel River Basin (QRB, ca. 12,000 km2) in central British Columbia. The overall research project will specifically focus on how geomorphological connectivity (e. g. linkages between land and rivers, and linkages within channels) influences the transfer of sediment and associated chemicals - like trace metals (i.e. arsenic, copper, zinc), nutrients (e.g. phosphorus) and particulate carbon - due to stressors acting in the QRB. One project will evaluate the role of storage elements (specifically glacial forefields, riparian buffers, floodplains, and channel beds) in controlling how sediment and associated chemicals move through landscapes that have been influenced by climate change and land-use activities. In particular, this project will determine if such storage elements attenuate and/or modify material flows and fates. A second project will employ a nested monitoring program in conjunction with sediment tracers, to follow the movement of sediment and chemicals downstream of specific land-use activities such as agriculture, forestry and mining. A third project will use existing spatially distributed models to examine the role of geomorphological connectivity on sediment and associated chemical responses to stressors at the watershed-scale, utilizing the empirical information obtained from the first two projects and an existing GIS platform available for the QRB. The work will provide an improved understanding of how watersheds respond to cumulative effects in a rapidly changing world, which will help to protect water resources and aquatic habitats in Canada.